The invention relates to a commutator motor with a retention device that retains a brush during assembly. Commutator motors of this type are provided, in particular, as drive motors for motor-driven pump units in automatic brake systems (ABS) in motor vehicles and must be protected from moisture.
In a motor-driven pump unit, especially for an ABS drive such as is known through EP 0 682 398 B1, for example, a vat-like motor housing is provided to seal the motor. The motor housing has an open side with an edge that rests axially against the pump housing. The vat-like motor housing is sealed on the apical side through a brush carrier plate in such a manner that the brushes, positioned on the brush carrier plate on the inner side of the motor, are not accessible upon assembly in the motor housing. During the assembly, the rotor and the commutator are mounted in the motor housing before the brush carrier plate is sealingly mounted.
A commutator motor with an axially flanged drive housing that is sealed against moisture is known from Laid Open German Application DE 42 35 962 C2. In this reference, a brush carrier plate with brushes that are displaceable against a commutator is disposed between the apical faces of a motor housing and a drive housing. The brush carrier plate simultaneously serves as a flat sealing element sealing against moisture between the apical faces of the motor housing and the drive housing.
Finally, U.S. Pat. No. 5, 444, 320 teaches an assembly procedure for a commutator motor in which brushes are initially held fixed in a retention position for the assembly by a sleeve encircling the commutator. Following assembly of the rotor, the brushes are released into their operational end position by axial displacing the sleeve.